The hyperfine field for a metal is coming mainly from the contact term
due to the induced spin-polarization by the magnetic field.
You should notice, that a field of 9 T is (for theoretical calculations)
an extremely small field, causing a very small spin-splitting of the
states near EF, which causes the HFF.
I suppose all you see is numerical noise.
Since only the states at EF are of interest (the field can only reoccupy
states within a few mRy (or less) around EF), you need to converge your
calculation with respect to:
a) the k-mesh (test MUCH larger meshes (10000, 50000 100000 k or more)
b) the magnetic field (increase it and test fields up to 1000 T), You
are not interested in the absolute number, but in ppm, i.e. the relative
induced field.
c) The angular momentum component of the hFF introduced by
case.vorbup/dn is NOT correct. I would even suggest that you put l=0 to
minimize the effect (or use -orbc with case.vorbup/dn , where all
elements are set to zero.)
d) In principle the orbital contribution should be obtainable from the
NMR-module of wien2k_13. However, also there we observed for metals that
it is very hard to converge with respect to k-mesh and the final results
(sum of spin and orbital contribution) does not seem right, while
spin-only has the correct magnitude (within 10% of the experiment). This
is an unresolved issue for us so far.
Am 07.10.2013 04:01, schrieb Jing-Han Chen:
Dear WIEN2k users and authors
We are currently working on the hyperfine field calculation by using
ORB package. In fcc aluminum case, we got 0.154 (KGAUSS) when the
following case.inorb and case.indm are used
case.inorb
3 1 0 nmod, natorb, ipr
PRATT, 1.0 mixmod, amix
1 1 0 iatom nlorb, lorb
9. Bext in T
0. 0. 1. direction of Bext in terms of lattice vectors
case.indm
-9. Emin cutoff energy
1 number of atoms for which density matrix is
calculated
1 1 0 index of 1st atom, number of L's, L1
0 0 r-index, (l,s)index
In order to confirm how the magnetic field is applied for the
multiple sites crystal, we made aluminum as a simple cubic with 4
inequivalent sites and we believe it should be physically identical to
fcc. The following case.inorb and case.indm are used.
case.inorb
3 4 0 nmod, natorb, ipr
PRATT, 1.0 mixmod, amix
1 1 0 iatom nlorb, lorb
2 1 0 iatom nlorb, lorb
3 1 0 iatom nlorb, lorb
4 1 0 iatom nlorb, lorb
9. Bext in T
0. 0. 1. direction of Bext in terms of lattice vectors
case.indm
-9. Emin cutoff energy
4 number of atoms for which density matrix is
calculated
1 1 0 index of 1st atom, number of L's, L1
2 1 0 index of 1st atom, number of L's, L1
3 1 0 index of 1st atom, number of L's, L1
4 1 0 index of 1st atom, number of L's, L1
0 0 r-index, (l,s)index
Both fcc and simple cubic are run by the same way (-orb -cc 0.00001).
A complete different HFFs are obtained as the following
:HFF001: 0.059 0.000 0.001
0.060 (KGAUSS)
:HFF002: -1.193 0.000 -0.010
-1.204 (KGAUSS)
:HFF003: 1.681 0.000 0.011
1.692 (KGAUSS)
:HFF004: 0.046 0.000 0.001
0.047 (KGAUSS)
We got four different HFFs which we thought they are supposed to be the
same. Also all of them are very far from the fcc result (0.154 KGAUSS).
Does anyone know why it happens?
Any suggestion and comment are appreciated.
--
Jing-Han Chen
Graduate Student
Department of Physics
Texas A&M University
4242 TAMU
College Station TX 77843-4242
jhc...@tamu.edu <mailto:jhc...@tamu.edu> <jhc...@tamu.edu
<mailto:jhc...@tamu.edu>> / http://people.physics.tamu.edu/jhchen/
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TU Vienna
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